High coercivity nanostructured networks

Films of Fe, Co, and Co35Fe65 alloy have been sputter deposited onto the surface of porous nanochannel alumina substrates producing nanostructured contiguous magnetic ''networks.'' Large room temperature coercivities have been measured which approximately scale with the bulk saturation magnetization of the material used. In the as-deposited state the largest coercivities (e.g., >1000 Oe for Co35Fe65) are observed in similar to 15-nm-thick networks deposited on the smallest commercially available pore size substrates (those having an average pore diameter of similar to 20 nm and a wall thickness of similar to 15 nm). Preliminary studies of the effects of annealing indicate that coercivities can be substantially increased (by as much as similar to 50%) with an appropriate post-deposition thermal treatment. (C) 1997 American Institute of Physics.